Calcium treatment is a critical process for liquid steel prior to casting. Cored wire technology enables the addition of calcium and other ferroalloys without harming the quality of the steel.
The use of calcium cored wires (pure Ca, SiCa or AlCa) improves the modification of inclusions (alumina to calcined calcium aluminates). It also reduces caster nozzle clogging and enables higher calcium yield.
An experimental Al-0.6% Ca-0.2% Zr-0.4% Fe-0.25% Si alloy was cast by electromagnetic casting (EMC) in the form of a rod 12 mm in diameter and 20 m long. It was cold drawn to obtain wire 3 mm in diameter and then cold rolled to obtain strip 2 mm thick for further analysis of its mechanical and electrical properties. EC of the cold rolled and drawn ACZ alloy reached
Adding core wire in steelmaking can increase the yield of alloy elements, reduce smelting cost and shorten the smelting time, as well as accurately control the content of ingredients. Furthermore, the CaSi core can purify molten steel and partially change the nature and shape of inclusions, thereby improving the quality and casting state of the liquid metal. Excessive reoxidation can also be avoided, which is harmful in terms of nozzle blockage, because high melting point calcium aluminates are more favourable than sulfide stringers.
A metallurgical wire with a core consisting of calcium silicate is used to feed the molten steel in continuous casting machines. It improves the quality of the finished product by eliminating lead contamination, preventing the formation of harmful gas in the process. The conductive core also increases the evaporation rate of the liquid steel, helping to prevent slag formation.
In addition, the calcium can disperse inclusions into a size that will not clog the continuous caster nozzle. It can also break up inter dendritic Al2O3 galaxies into fine, Type III inclusions.
The research was conducted using the FEM software ANSYS Workbench with FLUENT Fluid Flow module (2019 R1 version, Ansys, Canonsburg, PA, USA). Numerical analysis of the continuous casting process simulated the temperature distribution in the graphite crystallizer and the copper cooling system as well as the temperature of the cast rod. The results obtained by the FEM simulations correlated well with the experimental part of the research carried out in the actual vertical continuous casting process in a graphite crystallizer.
Pure calcium has a high affinity for oxygen and sulfur in the steel melt. It forms oxides CaO, oxysulfides CaS and sulfides CaSO3. It also aids de-oxidation and desulphurization. However, due to its low density and low boiling point, it is difficult to add directly into the steel melt without using cored wires.
Incorporating cored wires into the steelmaking process is the best way to introduce calcium into the liquid metal. This is because cored wires have a high penetration capability and can be injected into the melt at higher speeds than conventional steel making processes.
The core of the wire is made from iron material while the sheath is made from alloy powders. There are barrier sections at the head and tail of the wire body. The barrier sections use metal powder that has low moisture absorption and does not pollute the molten steel. The specific filling weight of the cored wire is determined by the metallurgists according to the needs of their steel mills.
When used in welding applications, cored wire improves the quality of welded products and increases productivity. Welding is only a portion of the production process, however, so any increase in productivity needs to be balanced with changes elsewhere in the workflow. Using metal-cored wire also lowers oxidation and provides higher impact strength.
Cored wire can also reduce the hydrogen content in molten steel to avoid long sulfide inclusions. It can aid in deoxidation, desulfurization, alloying and inclusion denaturation of continuous casting steel.
When choosing a cored wire for your application, be sure to choose the right size. Too large a core can cause weld defects and shorten the service life of your wire feeder. Additionally, when using tubular wires for cored welding, use V-knurled drive rolls to help prevent crushing. The V-knurled drive rolls have small teeth to grip the core wire and allow you to apply less tension. This will result in a cleaner weld and less spatter and slag.
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